Dan Foss raised another interesting point about the switch from rye
to wheat as a major basis for the diet. Recently, work in Scotland,
where the shift from an oat-based diet to wheat-based did not occur
until about 1760, with the final subjugation of the scots by the brits,
has shown that there was a significant increase in the incidence of
ciliac disease (an allergy to the glutens in wheat that can prove fatal
if not recognized) at the time of the dietary switch. Whether such
an increase also occurred in the English and other northern European
populations when the dietary shift occurred there has not been studied,
and perhaps would be very difficult to document because the disease
leaves no obvious pathological identifiers on the skeleton and it is
unlikely that the medical records of the day were good enough to see
an changes recorded there. One can speculate, however, that such
increases likely did happen because of the similarity of the genotypes
throughout northern Europe. If so, there is one more factor that
helped to maintain lower populations during the late middle ages.
bonn